/Engine/Source/Runtime/SlateCore/Public/Debugging/SlateDebugging.h
Called as soon as the element is added to the element list. NOTE: These elements are not valid until the widget finishes painting, or you can resolve them all after the window finishes painting.
typedef TMulticastDelegate_TwoParams< void, const [FSlateWindowElementList](API\Runtime\SlateCore\Rendering\FSlateWindowElementList) &, int32 > FDrawElement